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FOR GENERAL READERS. 



Vol. II.— No. i. 



FRIDAY, JULY 6th, 1888. 



r Weekly, Price 3d. 

 L By Post. SJd- 



Scientific Table Talk 



The Thirty-six inch Telescope of the 

 Lick Observatory (illus. ) 



Photography by Night with Lightning 

 Powder {illus.) 



Diamonds from the Heavens ... 



General Notes 



Buds (z7/z<.f.) 



Poisonous Dyestuffs ... _, 



The Cultivation of the Osier ... 



Natural History : 



A Curious Parallel {illus.) 



The Poison of Bees 



Application of Sulphate of Copper 

 to Fruit Trees ... 



PAGE 

 I 



4 

 6 



1 



9 



10 



II 

 12 



CONTENTS. 



PAGE 

 • 13 



Miscellaneous Notes 

 Poisons in the Workshop 



Reviews : 



Betrieb der Galvanoplastic mit 

 Dynamo - electrischen Masch- 



nen 14 



A Manual of Orchidaceous Plants 14 

 Transactions of the Manchester 

 Geological Society ... ... 15 



Abstracts of Papers, Lectures, etc. : 



Manchester Microscopical Society 15 



Royal Society 16 



London Mathematical Society ... 16 



Royal Meteorological Society ._ 16 



PAGE 

 Hawick Scientific and Philosophi- 

 cal Society ... ... ... 17 



The Social Condition of the Babylonians 17 

 The Chemistiy of Fire and Fire Pre- 

 vention 1 8 



Correspondence : 



The Duration of Sunshine — The 

 Common Sparrow — Arsenic in 

 Cretonne ... ... ... ... 20 



Recent Inventions 

 Technical Education Notes 

 Sales and Exchanges 

 Selected Books ... 

 Meteorological Returns 



22 



23 

 24 

 24 

 24 



SCIENTIFIC TABLE TALK. 



By W. Mattieu Williams, F.R.A.S., F.C.S. 



At the Southampton meeting of the British Association 

 (1882) Schwedoft's theory of hail was brought forward 

 by Prof. Sylvanus Thompson, and opposed by Sir 

 William Thomson, who stated that a hailstone passing 

 through our atmosphere would do as much work as 

 would raise the water of which it is composed 13,000 

 centigrade degrees, or, otherwise stated, 13,000 times as 

 much work as would raise it one degree. This being 

 demonstrated mathematically, of course settles the ques- 

 tion mathematically. To some people such demonstration 

 is final, and therefore the idea that a lump of ice can 

 enter our atmosphere as meteoric matter, pass through it 

 and reach the earth as ice, is, as Sir W. Thomson said, 

 " a manifest absurdity." 



But we know that lumps of iron do thus enter the 

 atmosphere, pass through it, and perpetrate the mani- 

 fest" absurdity by surviving in solid form this ordeal of 

 fire. 



In the case of iron the absurdity is even greater than 

 that of water, as the quantity of heat demanded for the 

 fusion of a given weight of iron is far greater than is 

 demanded for the fusion and evaporation of the same 

 weight of water. Note that we have here a question of 

 quantity of heat corresponding to work done, not one of 

 mere temperature. 



The specific heat of water is nine times greater than 

 that of iron, the quantity of heat demanded for raising 

 a pound or any other weight-unit of water one degree 

 will raise the same quantity of iron nine degrees, or 

 nine times that quantity one degree. Therefore 

 (assuming the figures of Sir W. Thompson to be cor- 

 rect) the heat generated as described would raise the 

 iron nine times 33,000 degs., or 297,000 degs. But iron 

 fuses at about i,6oo" C. How, then, does it contrive 

 to reach the earth in a solid state ? 



A simple experiment answers this question. Take a 

 chisel or other hardened steel tool and press it against a 

 rapidly rotating dry grindstone. Here work willbedone in 



arresting the motion of the grindstone, and heat will be 

 evolved in quantity exactly proportionate to the amount of 

 mechanical motion arrested, i.e., the motion of the grind- 

 stone. Both grindstone and steel will be heated ; the 

 temperature of the steel will be far higher than that 

 of the grindstone because it is more concentrated on 

 the smaller surface of the steel. The evidence of this 

 high temperature will be supplied by the brilliant com- 

 bustion of the particles of steel torn from the chisel, 

 and by the softening of that part of the steel in contact 

 with the grindstone. A chisel thus treated, as every 

 practical workman knows, is spoiled by such softening, 

 and therefore he always fits up his grindstone in a 

 trough of water so that a film of cold water shall adhere 

 to the rubbing surface. Itinerant grinders who sharpen 

 other people's knives and scissors may omit this, as the 

 softening of these is " good for trade ; " the softened 

 edges rapidly become blunt and require regrinding. 



A further examination of the chisel, if fairly bright, 

 will supply further instruction. It will show that the 

 heat thus developed is generated at the surface whereon 

 the force which did the work was applied. The well- 

 known colours whereby the workman determines the 

 temperature of heated steel will be displayed, the blue 

 just beyond the ground face, then the purple, then the 

 nut-brown and straw colour, etc. Two comparative ex- 

 periments may be made, one in which the grinding 

 operation lasts but a very short time, when it will be 

 seen that the bands of colour will be very narrow ; if 

 in the other experiment the grinding be continued for a 

 much longer time, the bands will be proportionately 

 broader, showing that time be required for the heat to 

 travel through the substance of the metal. 



The case of the meteorite passing through the air is 

 analogous, the air here representing the grindstone as 

 regards its friction on the surface of the meteorite, which 

 frictiondoes the work of reducing the velocity of the motion 

 of the mass. The effect is shown accordingly on the sur- 

 face, as may be seen by an examination of the fine collec- 

 tion of specimens at the end of the mineral room of the 

 British Museum (Natural History Department, South 



